This invention relates to a liningless braking mechanism that utilizes mechanical/hydraulic damping to absorb energy.
Vehicle brake assemblies typically include brake linings that interact with either a brake drum or a brake disc to brake a vehicle. The brake linings are supported on plates and are controlled by actuators, which bring the linings into contact with the brake drum or disc utilizing frictional forces to stop or slow a vehicle.
These linings wear over time due to the frictional contact. For heavy duty braking applications, the linings wear out quickly and need to be replaced often. This is very expensive and results in significant vehicle down time.
Another disadvantage with brake linings is that as the linings wear, the brake becomes out of adjustment. Thus, the necessary brake pedal stroke length to actuate the brake will increase as the linings wear. To account for this, brake assemblies include slack adjusters that adjust the position of the brake linings to try to keep a constant distance between the surface of the linings and the brake drum or disc surface. These slack adjusters take up valuable packaging space and increase assembly time and cost.
Thus, it is desirable to provide a braking assembly that eliminates the need for brake linings and brake drums/discs and overcomes the above mentioned deficiencies.
This braking mechanism utilizes a unique concept for dissipating energy from a vehicle. This unique braking mechanism eliminates the need for brake drums and brake linings. A mechanical/hydraulic damping system is used to absorb energy during braking and can be actuated by conventional methods or with brake-by-wire actuation.
In a disclosed embodiment of this invention, the liningless braking mechanism is incorporated into an axle having a non-rotating axle member and a rotating axle member for rotation about an axis. A base plate is fixed to the non-rotating axle member and an actuation plate is mounted for selective rotation about the axis. A cam is mounted for rotation with the rotating axle member and a plurality of dampers are used to perform braking actuations. The dampers each include a mounting portion in contact with the actuation plate to move the dampers relative to the base plate and include a movable distal end for selectively engaging the cam. An actuator selectively rotates the actuation plate to engage the distal end against the cam to perform a brake actuation.
In a preferred embodiment, the actuation plate radially adjusts the distal ends relative to the cam to control braking force. The base plate is comprised of a circular disc having a plurality of radially extending orientation slots formed about the circumference and the actuation plate is comprised of a circular disc having a plurality of curved actuation slots formed about the circumference. The orientation slots restrict radial damper movement toward an axle center and the actuation slots determine the rate of damper actuation during braking.
In a further preferred embodiment, the cam includes a plurality of lobes formed about the circumference for engagement with the distal ends during braking. The actuator includes a motor and gear drive for selectively controlling rotation of the actuation plate about the axis to adjust the position of the distal ends relative to the cam.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.